GTAW of Aluminum

[astaindsoul5446]

Very nice write up. Thank you for taking the time to write this, and thank you to who ever made this a sticky.

[Hunterdan]

I attempted to weld my transmission case with the HI FREQ box connected to my AC/DC machine.I had no problem as far as function however I had big problems with cracking after welding.I preheated the case with a propane torch a few times for cleaning and to expose any cracks.Cracks were identified and welded successfully.I had two spots where the case `was worn through.I managed to weld these spots up by building up the edges and had good solid cover.The cracks started after the the holes were filled.Initially they ran parallel with the weld but outside of the fillet.I tried to gouge the crack and fill it but after I did that, new cracks appeared and ran perpendicular and were very pronounced,so much so that I feel that there is too much to repair. i would appreciate opinions.Thanks,Ron

Hi
Ron I'm new to forum and haven't done much welding in a long time but back when I was welding and im just asuming your trans case is cast alum,when ever we welded cast alum or any others type of cast material if it seemed to weld ok it was probably the rate at which the two metals cooled down (ie filler metal and the surounding cast material) which made it crack we used heating pads after welding was finished to hold heat in and we kept the whole pc warm untill all the welding was complete then did a controlled cool down , just my thoughts on it .

[chevydyl]

Well,I have determined that I don't have a transformer in my machine so I connected the sensing wire to my work piece and Viola, she works I couldn't do any real welding because I thought that I had some Alum Tig wire and I don't so I will have to wait a couple of days.

something I did try and was quite surprised with is that I used an Alum Flux dc rod ,4043, on DC reverse polarity with my tig torch and actually got a pretty decent bead.I was surprised that the flux didn't contaminate my puddle and the flux chipped off easily.

I will have to do some experimenting.Ron

Yes u do have a transformer In your machine. In fact so do inverters An inverter works this way ac input rectified to dc then inverted into ac then back to dc this sequence allows the use of a much smaller transformer and also allows filtering to make the arc much smoother. So the machine you have is old school with the big transformer. Welding machines wouldn't be possible without transformers. Technology has allowed engineers to create the same output amperage with smaller lighter components

[chevydyl]

Well,I have determined that I don't have a transformer in my machine so I connected the sensing wire to my work piece and Viola, she works I couldn't do any real welding because I thought that I had some Alum Tig wire and I don't so I will have to wait a couple of days.

something I did try and was quite surprised with is that I used an Alum Flux dc rod ,4043, on DC reverse polarity with my tig torch and actually got a pretty decent bead.I was surprised that the flux didn't contaminate my puddle and the flux chipped off easily.

I will have to do some experimenting.Ron

Yes u do have a transformer In your machine. In fact so do inverters An inverter works this way ac input rectified to dc then inverted (transformer)into ac then back to dc this sequence allows the use of a much smaller transformer and also allows filtering to make the arc much smoother. So the machine you have is old school with the big transformer. Welding machines wouldn't be possible without transformers. Technology has allowed engineers to create the same output amperage with smaller lighter components

[Donald Branscom]

This is the byproduct of me having way to much time on my hands, and noticing that about every week the same questions pop up. Hopefully this can shed some light about the mystery and general misconceptions about TIG welding of aluminum.

Polarity: AC current consists of a positive and negative portion, and alternates very rapidly between the two. This produces the "buzzing" sound that you hear, and what contributes to the nature of the AC arc. The AC balance control determines how much time is spend on either portion, a value higher on the negative side will giver better penetration and arc stability with decreased cleaning action, and vice-versa.

The positive portion of the wave (electrode positive) puts about 70% of the heat generated into the tungsten, this causes the tungsten to melt and beings to form a ball at the end. This portion of the wave is also what produces the cleaning action, in which ions bombard the surface of the material, removing some surface contaminates. DCEP can be used for welding of very thin aluminum but the tungsten will rapidly overheat.

The negative portion of the wave (electrode negative) puts about 70% of the heat generated into the workpiece, yielding much better penetration. This also enables the tungsten to better retain a point which makes the arc more stable and easier to control. This part does not offer any cleaning action. DCEN welding can be done on aluminum but it requires removal of all surface contaminates and generally done with helium shielding gas. (I dont know why, if any one can shed some light on this than im all ears)

Shielding Gas: 100% Argon is the most common, while mixtures of Ar and He can be used to achieve greater heat input. Argon is preferred because it is cheaper than He, very dense (better cleaning action) and produces a stable arc. Any mixture containing O2 or CO2 cannot be used because of the rapid formation of aluminum oxides, along with the rapid erosion of the tungsten.

Tungsten: The electrodes used on AC welding vary greatly with personal preference, but I do not know of any commonly found electrode that cannot be used. Some of the more popular ones include 2% ceriated, 2% thoriated, 1.5% lanthinated and pure tungsten. Pure tungsten is not required for use on any machine, in fact most inverter machines will not proper functionally with pure tungsten.

Forming a ball on the end of the electrode is not necessary, often it is preferred to weld with a slightly blunted point. If the ball grows too large and the arc seems unstable, stop welding and regrind the tungsten. If it continues, either decrease amperage or go to a larger tungsten diameter.

AC Controls: Older machines will likely have a simple balance control which was explained earlier. Newer inverter machines typically have an additional frequency control. This allows the user to adjust the amount of times (per second) that the arc switches from EP-EN. The standard is 60Hz, but increasing this ,typically >120Hz will stabilize the arc, making it "stiffer" and increasing penetration while reducing the width of the weld pool.

This is by no means the definitive guide, obviously I hardly even touched the surface. If you have something to add, do me a favor and just make it easy to read but feel free to add it in here. The goal is to make this a one-stop-shop for aluminum. If you disagree with something, PM me and we'll work it out.

That's all for now, more to come tomorrow.

You have some misinformation.
Helium gas is used for welding aluminum weldments that are thicker than 1/4 inch.
Different gasses do different things.
Argon keeps a stable arc and acts to keep oxygen away.
Helium gets better penetration on thick weldments.
Co2 gas helps to cool the weld and to sheild the weld.

You need to look up what each gas is used for. It's purpose.


ALSO: On a full box of tungsten if you read it it tells you what each type of tungsten is used for and why.


Just keep reading more stuff. But do not rely on what people tell you. Look it up yourself.

[shovelon]

You have some misinformation.
Helium gas is used for welding aluminum weldments that are thicker than 1/4 inch.
Different gasses do different things.
Argon keeps a stable arc and acts to keep oxygen away.
Helium gets better penetration on thick weldments.
Co2 gas helps to cool the weld and to sheild the weld.

You need to look up what each gas is used for. It's purpose.


ALSO: On a full box of tungsten if you read it it tells you what each type of tungsten is used for and why.


Just keep reading more stuff. But do not rely on what people tell you. Look it up yourself.

Not to be snipy, but your post contains some misinformation.

1. Not all boxed tungstens goes into detail for usage(chinese).

2. Co2 is not used with tig welding, let alone alum tig.

3. Helium can be used on all thicknesses of alum if so desired. Smaller tig machines can benefit if hotter weld is needed. 100% helium is used in DCEN welding of alum of all thicknesses.

[Steel buildings]

I don't know whether I have a transformer or inverter sort machine.the manual says that provided one it is a transformer machine then I may as well unite the sensing wire to a 115v melded association inside the welder and the fan association being the coveted spot,however the wiring plan basically indicates the sensing wire being associated with the work side or negative side of the welding machine

[Deadman]

Well done,
The information that was given was great for the uninformed....Way to go.....

[mike837go]

I wish I knew about aluminum SMAW before I bought the wrong TIG welder!

[blueweld59]

It may not be total a aluminum casting, you could check the content of the base metal and change you filler rod if needed, keep your heat as low as possible.

Swanny

[Willie B]

This is the byproduct of me having way to much time on my hands, and noticing that about every week the same questions pop up. Hopefully this can shed some light about the mystery and general misconceptions about TIG welding of aluminum.

Polarity: AC current consists of a positive and negative portion, and alternates very rapidly between the two. This produces the "buzzing" sound that you hear, and what contributes to the nature of the AC arc. The AC balance control determines how much time is spend on either portion, a value higher on the negative side will giver better penetration and arc stability with decreased cleaning action, and vice-versa.

The positive portion of the wave (electrode positive) puts about 70% of the heat generated into the tungsten, this causes the tungsten to melt and beings to form a ball at the end. This portion of the wave is also what produces the cleaning action, in which ions bombard the surface of the material, removing some surface contaminates. DCEP can be used for welding of very thin aluminum but the tungsten will rapidly overheat.

The negative portion of the wave (electrode negative) puts about 70% of the heat generated into the workpiece, yielding much better penetration. This also enables the tungsten to better retain a point which makes the arc more stable and easier to control. This part does not offer any cleaning action. DCEN welding can be done on aluminum but it requires removal of all surface contaminates and generally done with helium shielding gas. (I dont know why, if any one can shed some light on this than im all ears)

Shielding Gas: 100% Argon is the most common, while mixtures of Ar and He can be used to achieve greater heat input. Argon is preferred because it is cheaper than He, very dense (better cleaning action) and produces a stable arc. Any mixture containing O2 or CO2 cannot be used because of the rapid formation of aluminum oxides, along with the rapid erosion of the tungsten.

Tungsten: The electrodes used on AC welding vary greatly with personal preference, but I do not know of any commonly found electrode that cannot be used. Some of the more popular ones include 2% ceriated, 2% thoriated, 1.5% lanthinated and pure tungsten. Pure tungsten is not required for use on any machine, in fact most inverter machines will not proper functionally with pure tungsten.

Forming a ball on the end of the electrode is not necessary, often it is preferred to weld with a slightly blunted point. If the ball grows too large and the arc seems unstable, stop welding and regrind the tungsten. If it continues, either decrease amperage or go to a larger tungsten diameter.

AC Controls: Older machines will likely have a simple balance control which was explained earlier. Newer inverter machines typically have an additional frequency control. This allows the user to adjust the amount of times (per second) that the arc switches from EP-EN. The standard is 60Hz, but increasing this ,typically >120Hz will stabilize the arc, making it "stiffer" and increasing penetration while reducing the width of the weld pool.

This is by no means the definitive guide, obviously I hardly even touched the surface. If you have something to add, do me a favor and just make it easy to read but feel free to add it in here. The goal is to make this a one-stop-shop for aluminum. If you disagree with something, PM me and we'll work it out.

That's all for now, more to come tomorrow.

A vast amount of information, thank you. Yet I have another question. I have an entry level inverter, (Diversion 180) and a big transformer, (old school Dialarc 250 HF outfitted with all bells and whistles available in 1984), The inverter is fixed at 72% EP or 28% EN. I was guessing the transformer would be 50%. Is this the case? Cleaning action doesn't seem greater, should it?

[Donald Branscom]

I attempted to weld my transmission case with the HI FREQ box connected to my AC/DC machine.I had no problem as far as function however I had big problems with cracking after welding.I preheated the case with a propane torch a few times for cleaning and to expose any cracks.Cracks were identified and welded successfully.I had two spots where the case `was worn through.I managed to weld these spots up by building up the edges and had good solid cover.The cracks started after the the holes were filled.Initially they ran parallel with the weld but outside of the fillet.I tried to gouge the crack and fill it but after I did that, new cracks appeared and ran perpendicular and were very pronounced,so much so that I feel that there is too much to repair. i would appreciate opinions.Thanks,Ron

What kind of transmission case?
Was the arc glow green? Normally the glow will be blue to red.

IF so it could have a very high zinc content and
welding supply stores sell a special filler wire for this application.

[Donald Branscom]

I wish I knew about aluminum SMAW before I bought the wrong TIG welder!

Which TIG welder did you purchase?
You can weld aluminum with SMAW but it has constraints also.
The welding electrodes are very expensive. Were about $60.00 per pound.

If you leave them out of the box one night, all of the flux will fall off of the electrode.
Very fragile.

[Donald Branscom]

Not to be snipy, but your post contains some misinformation.

1. Not all boxed tungstens goes into detail for usage(chinese).

2. Co2 is not used with tig welding, let alone alum tig.

3. Helium can be used on all thicknesses of alum if so desired. Smaller tig machines can benefit if hotter weld is needed. 100% helium is used in DCEN welding of alum of all thicknesses.

I mentioned CO2 ,because it is one of the common welding gases. Not because I thought you would use it with the TIG process.

Yes, you CAN use Helium in thinner smaller sections, but it is very expensive.

[MinnesotaDave]

Which TIG welder did you purchase?
You can weld aluminum with SMAW but it has constraints also.
The welding electrodes are very expensive. Were about $60.00 per pound.

If you leave them out of the box one night, all of the flux will fall off of the electrode.
Very fragile.

Flux falls off? My local store has them open on a shelf to sell just how many you want.

That's how I bought them when I needed a few.

[ManoKai]

http://www.maxal.com/files/QuickSite...g_6-11_doc.pdf

solid overview on welding Al using GTAW (and GMAW).

[Willie B]

I know it is now an old thread If you see this Snowboarder88, Thank you.

[jstasney]

I attempted to weld my transmission case with the HI FREQ box connected to my AC/DC machine.I had no problem as far as function however I had big problems with cracking after welding.I preheated the case with a propane torch a few times for cleaning and to expose any cracks.Cracks were identified and welded successfully.I had two spots where the case `was worn through.I managed to weld these spots up by building up the edges and had good solid cover.The cracks started after the the holes were filled.Initially they ran parallel with the weld but outside of the fillet.I tried to gouge the crack and fill it but after I did that, new cracks appeared and ran perpendicular and were very pronounced,so much so that I feel that there is too much to repair. i would appreciate opinions.Thanks,Ron

Hi nmaineron,
You didn't specify what type of filler rod you were using, ie E4043, E5356, etc?" E4043 is a better choice since it isn't as prone to crack. Also, welding wide gaps all at once and aluminum usually don't work well. Excessive heat in the HAZ results in excessive shrinkage. Too much causes cracks longitudinally with the weld in that wide gapped area.

A transmission case is inherently a very contaminated surface/sub surface area to weld aluminum because of the transmission oil within the case run at high temperatures. The oil will be absorbed within the heat expanded pores of the aluminium making it very difficult to completely remove for welding.

Hot Steam Power washing the warmed up pre-heated (175 - 180 degree) case with a very strong degreaser will help in that regard rinsing very well with clear water. If you have access to an old kitchen oven large enough to hold the case, pre-heat the case and soak it on that heat for 24 hours at 250 - 300 degrees. That will burn out/vaporize the oils still hidden in the pores of the aluminum. If not, heat lamps clipped to the rim and pointed inside the case which is covered with a fire resistant blanket works well. A portable BBQ grill temp gauge helps monitoring the temps.

Steam Power Wash/scrub with w/ clean stainless brush the areas to weld again with a good strong degreaser rinsing with clear water. Blow dry with compressed air. Bevel and prep the areas to weld. Use tight fit ups of the welding areas. Pre-heat the case to at least 120 degrees before welding. Don't weld on a cold case. If you have gaps, build up the areas to weld a little at a time on each side. Let the areas cool to less than 200 degrees before resuming the welding.

If penetration to the back side of the weld is happening, use a backing gas shield of argon, as well, to prevent oxidation. Oxidized aluminum requires much more heat to maintain a liquid puddle. Excessive Heat is your enemy.

If you are welding and cut into a pocket of oil in a pore (a black area that out gasses), stop. Burr out the contamination, pre-heat, clean and de-grease, rinse, blow dry and start again.

Don't weld with a tungsten that's been contaminated with aluminum. Your depositing aluminum oxide in the puddle contaminating the weld. This will cause a crack and excessive heat to keep the puddle liquid. Clean the tungsten, the contaminated weld puddle and start again.

That's our experience with these aluminum cases.
They demand the utmost attention to cleanliness and detail of the welding procedure to successfully weld without cracking.
Following these tips described, to the letter, should improve your results drastically.

I've found the 3M Scotch Brite discs mounted to a 4 1/2 grinder to be excellent cleaning an aluminum surface of oxidation.

http://www.amazon.com/3M-9682-SandBl...d_sim_sbs_hi_3

I hope these tips help.

[bobhdus]

Flux falls off? My local store has them open on a shelf to sell just how many you want.

That's how I bought them when I needed a few.

I bought a couple of boxes of aluminum smaw electrodes at a garage sale, and they are probably a couple of years old. One box was opened but full and the flux is fine. Regardless, aluminum smaw electrodes may be used with oxyactylene rig to weld aluminum. It should work just fine just leaving the flux on the rod.

[soutthpaw]

When we visited Multiplaz, I actually took some SMAW aluminum rods with me and used then to weld aluminum with their plasma welder. Left a bunch with their tech guy to play with.

Sent from my SCH-I545 using Tapatalk

[Mikael]

Nice information. Thanks to all for sharing this post.

[Willie B]

Somebody mentioned a machine with a 30-70% EN range. I can't think 70% EN would be very versatile. I would use it with old, salvaged material. Clean material uses 75-85%. This is not true of transformer machines from 30 years ago, these machines use sine wave power, the arc virtually dies twice a cycle, leaving only the superimposed high voltage, high frequency current. Reestablishing current is easier in the EN half cycle where the electrons leap from the tip of the pencil shaped tungsten which is not oxidized. Establishing an arc from the broad surface of aluminum work piece coated with oxidation, or contamination isn't as effective. Sine wave, 60 cycle welders for the most part are 50/50 balance, but do not behave like inverter welders at 50/50 balance. Square wave welders switch polarity so quickly the ionization is still present, the EP half cycle is easily established. Comparison of balance will vary with cleanliness of aluminum. I exaggerate saying the Dynasty will weld through paint, but it is amazing!

[Johnny Dixon]

oh man there is some good stuff on here. wish i could have found this before the semester started, ha ha. Just finished the semester learning gtaw on mild steel, stainless steel and aluminum. I didn't do so hot on the aluminum, but i was fascinated with it. I got as far as Tee, lap, and corner joints running vertical. I couldn't finish in class but I saved up enough for a used Harley and bought a Dynasty 200 DX to use at home instead My priority is to make sure I learn how to weld and hopefully use it to make enough to get the bike later. Sorry, got off track. So here's what Im doing: on 1/16 aluminum coupons around 7" long using 1/16 4043 filler, sometimes 1/16 2% lanthinated, sometimes 1/16 2% ceriated; when using the schools syncrowave 250: 1/8 pure tungsten with 1/8 4043 filler , sometimes gas lens, sometimes not. I kept the tungsten balled 1- 1 1/2 times the diameter and ran anywhere from 80 amps to 110 amps. From what i saw on the tee joint (flat and vert), the arc would move back and forth between the two plates etching a little over here, a little over there, but i couldnt keep the arc in the joint to get a puddle, and if i started too much on one side I would have trouble with etching all the way up it. Also I would stay on it so long it could get really hot. Not burn through, but just get really really hot. I'd get maybe 2 inches up before it got too hot to continue and i would have to stop. I tried to shape the arc a little with the dynasty (balance and pulsing, etc., which helped some) but soon put it back to default settings because at this point i felt like it was just cheating. It looked like, there wasn't any real penetration, so after reading this thread, Im wondering if i should've just turned the amps up some? But it seemed counter intuitive because it was already so hot. I did manage to get a couple of beads decent enough to turn in for a grade, but there was 4 restarts from getting too hot and the weld face was around 3/32 wide with no distinct ripples. I mentioned all the different tungstens but results were similar with everything i tried.
My lap joint (flat and vert), using same set up, fared a lot better and I had a stack of dimes.......ish with pad plates in all positions. Is the tee joint really so different than the others, or is something not sinking in through this thick skull of mine.
oh also, i never felt like the puddle was established enough to walk the cup, so it was virtually all freehand.
this will be my first real post, besides intro, so if its not enough info or too much of something unnecessary then just let me know and thanks for everything so far.

[soutthpaw]

You don't want balled tungsten with an inverter. Sharpen it to a point. You could easily use 3/32 or 1/8 tungsten sharpened to a point to weld those coupons. Lanthanated is a great choice

[Johnny Dixon]

You don't want balled tungsten with an inverter. Sharpen it to a point. You could easily use 3/32 or 1/8 tungsten sharpened to a point to weld those coupons. Lanthanated is a great choice

only balled the pure tungsten when running on the syncrowave. the quick reference that came with the dynasty said pure wasn't reccomended and keep the tungsten sharp with a flat. but still, similar results across both machines.